Intracellular cholesterol trafficking and membrane remodeling in physiology and disease

Date
Monday April 22, 2024
Time:
10:00am - 11:30am
Location
114 Morgan Hall
About this event




Cholesterol trafficking in the cell is a key event in the control of cellular cholesterol homeostasis. Given the role of endoplasmic reticulum (ER) as the intracellular cholesterol sensor, comprehending the mechanisms involved in the delivery of exogenous cholesterol to the ER is crucial. Our research identified a family of proteins called Aster/Gramd1, which participate in non-vesicular cholesterol transport from the plasma membrane to the ER. We recently reported a role of these protein in the absorption of diet-derived cholesterol. Intestinal absorption is an important contributor to systemic cholesterol homeostasis. Niemann-Pick C1 Like 1 (NPC1L1) assists in the initial step of dietary cholesterol uptake, but how cholesterol moves downstream of NPC1L1 was unknown. We found that Aster-B and Aster-C are critical for non-vesicular cholesterol movement in enterocytes. These proteins cooperate with NPC1L1, which initially deposits cholesterol into the apical membrane, thereby increasing the local pool of accessible cholesterol. This event engages Aster-B and -C, that facilitate the movement of cholesterol to ER, where it undergoes esterification and subsequential incorporation into chylomicrons. The recruitment of Asters to membranes necessitates interaction with anionic phospholipids in the plasma membrane. This raises intriguing questions about the interplay between membrane phospholipid remodeling and the regulation of intracellular cholesterol trafficking.